Quarkhadron phase transitions in the viscous early universe
Abstract
In the standard hot big bang theory, when the Universe was about 110μs old, the cosmological matter is conjectured to undergo quantum chromodynamics (QCD) phase transition(s) from quark matter to hadrons. In the present work, we study the cosmological quarkhadron phase transition in two different physical scenarios. First, by assuming that the phase transition would be described by an effective nucleation theory (prompt firstorder phase transition), we analyze the evolution of the relevant cosmological parameters of the early universe (energy density ρ, temperature T, Hubble parameter H, and the scale factor a) before, during, and after the phase transition. To study the cosmological dynamics and the time evolution, we use both analytical and numerical methods. The case where the Universe evolved through a mixed phase with a small initial supercooling and monotonically growing hadronic bubbles is also considered in detail. The numerical estimation of the cosmological parameters, a and H for instance, shows that the time evolution of the Universe varies from phase to phase. As the QCD era turns to be fairly accessible in the highenergy experiments and the lattice QCD simulations, the QCD equation of state is very well defined. In light of these QCD results, we develop a systematic study of the crossover quarkhadron phase transition, and an estimation for the time evolution of the Hubble parameter during the crossover.
 Publication:

Physical Review D
 Pub Date:
 April 2012
 DOI:
 10.1103/PhysRevD.85.084032
 arXiv:
 arXiv:1108.5697
 Bibcode:
 2012PhRvD..85h4032T
 Keywords:

 04.50.h;
 98.80.Bp;
 98.80.Cq;
 98.80.Jk;
 Higherdimensional gravity and other theories of gravity;
 Origin and formation of the Universe;
 Particletheory and fieldtheory models of the early Universe;
 Mathematical and relativistic aspects of cosmology;
 Astrophysics  Cosmology and Extragalactic Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 27 pages, 17 figures, revtex style (To appear in Phys. Rev. D). arXiv admin note: text overlap with arXiv:grqc/0404045